File:Preliminary report on the geology of east central Minnesota including the Cuyuna iron-ore district (1918) (14784110683).jpg

Identifier: preliminaryrepor00hard (find matches)
Title: Preliminary report on the geology of east central Minnesota including the Cuyuna iron-ore district
Year: 1918 (1910s)
Authors: Harder, Edmund Cecil, 1882- Johnston, A. Walfred, author Geological Survey (U.S.)
Subjects: Geology Iron mines and mining
Publisher: Minneapolis, University of Minnesota
Contributing Library: Wellesley College Library
Digitizing Sponsor: Boston Library Consortium Member Libraries

View Book Page: Book Viewer
About This Book: Catalog Entry
View All Images: All Images From Book
Click here to view book online to see this illustration in context in a browseable online version of this book.

Text Appearing Before Image:
ther Lake Superior iron-oredistricts. However, in the Cuyuna district, quartzite lenses and layershave been encountered in only a few places, and it has not yet been pos-sible to determine any relationship between the scattered occurrences. It is possible that, as exploration work progresses, and individual bedsof different rocks are traced along the strike, some orderly arrangementof layers may be found to exist. For the present, however, any attemptedcorrelation is largely speculative. Deerzvood iron-bearing member.—The iron-bearing rocks of the Cuy-una district present a variety of lithologic types. Among the more com-mon types are hematitic and limonitic chert, hematitic and limonitic slate,cherty and argillaceous ferrous carbonate, siliceous magnetitic slate,amphibole-magnetite rock, green amphibolitic slate, jaspilite, dark blue, 10* Cheney, C. A., Jr., Structure of the Cuyuna iron-ore district of Maoocoote: Eng. andMin. Jour., vol. 99, pp. 1113-1115, June 26, 1915. PLATE XVII
Text Appearing After Image:
THE CUYUNA IRON-ORE DISTRICT US red, brown, black, and yellow iron ore, black, red, and brown manganifer-ous iron ore, green chloritic schist, and dark red hematitic schist. Limonitic and hematitic chert are the most characteristic iron-bearingrocks in the Lake Superior region. In the Cuyuna district they are mostabundant in the north range where they compose the principal part of theiron-bearing layers. However, they are common on the south range aswell. They usually consist of interlaminated white, pink, or gray chertand hematite or limonite, the chert and iron oxide occurring in alternatelayers. (Plates XVII and XVIII.) In some parts of the rock the hematiteor limonite laminae are fairly pure, and elsewhere they are very siliceous.In many places the iron oxide present is merely a stain or an impregna-tion. Thus there are all gradations of ferruginous chert from siliceousiron ore to chert containing only a small percentage of iron oxide. Muchof the ferruginous chert, instead of bein

Note About Images